Crash Type Analysis

Provided below are the definitions of the 14 crash groups included in the BIKESAFE application (13 are included in the interactive crash matrix). For any crash group, there are multiple problems or possible causes that may have led to the crash. The following section provides examples of a few possible causes and problems for each group and some of the countermeasures within BIKESAFE that may be applicable. Neither the list of problems and possible causes nor the suggested countermeasures are to be considered comprehensive. Practitioners will still be required to supplement the analysis and recommendations with their own investigations and knowledge of local policies and practices.

In addition to selecting countermeasures based on the crash problems or possible causes listed below, a matrix of performance objectives is also provided for practitioners to select appropriate countermeasures for consideration based on specific challenges at the study location.

1. Motorist Failed to Yield — Signalized Intersection

The motorist enters an intersection and fails to stop at a traffic signal, striking a bicyclist who is traveling through the intersection on a perpendicular path. Typically, no turning movements are made by either party, except for a possible right turn on red. Many of these crashes involve bicyclists who are riding the wrong way against traffic, either in the roadway or on the sidewalk approaching the intersection.

Possible Cause/Problem #1:
Motorist drives through a red signal without stopping. The motorist could be speeding and unable to stop in time, trying to get through the intersection on a yellow or amber signal indication, disregarding the signal, or failing to see the red signal.

Possible Cause/Problem #2:
The motorist drives out after stopping for a red signal, into the path of an oncoming bicyclist. The motorist may be making a right turn on red and fails to look to the right to see an approaching bicyclist. The bicyclist could be riding the wrong way in either the roadway or on the sidewalk.

2. Motorist Failed to Yield — Non-Signalized Intersection

The motorist enters an intersection without properly stopping or yielding at a stop sign, yield sign, or uncontrolled location, striking a bicyclist who is traveling through the intersection on an initial perpendicular path. Many of these crashes also involve bicyclists who are riding the wrong way against traffic, either in the roadway or on the sidewalk approaching the intersection.

Possible Cause/Problem #1:
Motorist fails to stop at a stop sign or yield at a yield sign or uncontrolled intersection. The motorist could be speeding or otherwise fail to observe correct right-of-way, including flagrantly violating sign control.

Possible Cause/Problem #2:
The motorist pulls out into the path of a bicyclist traveling through the intersection after first stopping (or slowing). The bicyclist could be riding the wrong way or on the sidewalk or both and ride into the intersection in the pedestrian crosswalk area. The motorist may pull out and fail to check or notice the bicyclist approaching (particularly from the right). The motorist may be turning right.

3. Bicyclist Failed to Yield — Signalized Intersection

The motorist enters an intersection without properly stopping or yielding at a stop sign, yield sign, or uncontrolled location, striking a bicyclist who is traveling through the intersection on an initial perpendicular path. Many of these crashes also involve bicyclists who are riding the wrong way against traffic, either in the roadway or on the sidewalk approaching the intersection.

Possible Cause/Problem #1:
The bicyclist rides into the intersection through a red signal without stopping. The bicyclist may be trying to rush through on an amber signal indication, fail to see the red signal, or choose to disregard the signal. The bicyclist may not want to interrupt momentum or stop for a signal with an excessively long delay or that does not detect bicyclists’ presence. Inexperience could also contribute to this type of crash. The signal may be more difficult to observe if the bicyclist is traveling wrong-way or riding on the sidewalk.

Possible Cause/Problem #2:
The bicyclist enters the intersection on a green or amber traffic signal indication but fails to clear the intersection when the traffic signal changes to green for the cross-street traffic. A multiple threat crash can also occur when the signal changes to green for the cross-street traffic and the bicyclist is struck by a motor vehicle whose view was obstructed by standing or stopped traffic in an adjacent lane.

Possible Cause/Problem #3:
The bicyclist rides into the intersection after stopping for a red signal and into the path of a motorist. The bicyclist may ride out after waiting for a green indication if there is no provision for bicycle detection or the delay is excessive.

4. Bicyclist Failed to Yield — Non-Signalized Intersection

The bicyclist enters an intersection and fails to stop or yield at a non-signalized intersection (typically controlled by a stop sign), colliding with a motorist who is traveling through the intersection. This group of crashes could involve a lack of understanding of the sign control, inexperience, or disregard for the sign.

Possible Cause/Problem #1:
Bicyclist fails to yield at a stop sign, yield sign or uncontrolled intersection. Sidewalk or wrong-way riding may exacerbate the problem by increasing the chances the bicyclist will not notice and obey sign control. Younger bicyclists tend to be disproportionately involved in this crash type.

Possible Cause/Problem #2:
The bicyclist rides out after stopping (or slowing). At a yield or two-way stop, the motorist could be speeding, the bicyclist may underestimate the time needed to start-up and get through the intersection, or the bicyclist may not detect an approaching motorist. At a four-way stop, the bicyclist may not understand right-of-way rules. A multiple threat situation can also occur at a non-signalized location.

5. Motorist Drove Out — Midblock

The motorist typically pulls out of a driveway or alleyway and fails to yield to a bicyclist riding along the roadway or on a parallel path or sidewalk. Two-thirds of these types of crashes typically involve a bicyclist who is riding the wrong way against traffic, either on the sidewalk or on the roadway.

Possible Cause/Problem:
The motorist pulls out of a residential or commercial driveway or alleyway and fails to yield to a bicyclist riding along the roadway, on the sidewalk, or on a parallel shared-use path. Visibility may be obscured by buildings, parked cars, trees and shrubs, signal control boxes, sign posts and a host of other things that can be found along the sidewalk or edge of the roadway. The motorist may also fail to look right before pulling out or fail to detect higher-speed bicyclists or those traveling wrong-way on the roadway or sidewalk.

6. Bicyclist Rode Out — Midblock

The bicyclist rides out from a residential driveway, commercial driveway, sidewalk, or other midblock location into the road and is struck by or collides with a motorist.

Possible Cause/Problem:
The bicyclist rides out from a residential driveway, commercial driveway, sidewalk, or other midblock location into the road without stopping or yielding and is struck by a motorist. This crash type is a common one for young children who fail to stop and scan for vehicles before crossing the road or pulling out into traffic. Motorists speeding through neighborhood streets increase the risk of being unable to avoid this type of crash, so traffic calming measures may be appropriate.

7. Motorist Turned or Merged Left into Path of Bicyclist

The motorist turns left into the path of an oncoming bicyclist or turns or merges left across the path of a bicyclist who is traveling straight in the same direction as the motorist. This crash can also involve motorists or bus or delivery vehicles pulling out of parking spaces or stops.

Possible Cause/Problem #1:
The motorist turns left into the path of an oncoming bicyclist. The problem frequently occurs at signalized intersections on roads with four or more lanes, but may occur at driveways and other non-signalized junctions. The left-turning motorist is waiting for a gap in oncoming traffic and fails to look for, see, or yield to the oncoming bicyclist.

Possible Cause/Problem #2:
A motorist turns or merges left across the path of a bicyclist who is traveling straight ahead. Many times this crash occurs at an intersection or driveway where the bicyclist is riding the wrong way against traffic or is riding the wrong way against traffic on the sidewalk. Reducing wrong-way riding would be a goal of bicyclist education and other countermeasures. Most general countermeasures are the same for these first two types of crashes.

8. Motorist Turned or Merged Right into Path of Bicyclist

The motorist turns right into the path of a bicyclist traveling in the same direction or a motorist turning right strikes an oncoming bicyclist who is riding against traffic. This crash can also involve motorists pulling into parking spaces, bus or delivery vehicle pull-overs, or motorists making right turns on red.

Possible Cause/Problem #1:
At an intersection, merge area, or driveway, the motorist turns or merges right across the path of a bicyclist who is traveling straight ahead in the same direction. The motorist may misjudge the speed of the bicyclist or believe (mistakenly) that the bicyclist should wait for them.

Possible Cause/Problem #2:
A motorist turns right, striking a bicyclist approaching from the opposite direction. The bicyclist is most likely riding the wrong way, against traffic, but could be legally riding on the sidewalk or an adjacent path or cycle track. This crash may involve a right-turn-on-red, with the bicyclist possibly violating a red signal since the crash type involves traveling on a parallel path to the motorist.

9. Bicyclist Turned or Merged Left into Path of Motorist

The bicyclist turns or merges left into the path of an overtaking motorist who is traveling straight ahead in the same direction as the bicyclist, or a bicyclist turning left strikes an oncoming motorist. This crash can also involve a bicyclist riding out from a sidewalk or path beside the road. The bicycle and the motor vehicle are initially on parallel paths.

Possible Cause/Problem #1:
The bicyclist turns or merges left from the right side of the roadway. The rider fails to see or yield to a motorist coming from behind and is hit by the overtaking motorist. The crash also could involve a bicyclist riding out from a sidewalk or path beside the road. Speed of overtaking vehicles may be a factor in this group of crashes. The motorist also may not see the bicyclist, or may not suspect that the bicyclist will turn in front in time to react.

Possible Cause/Problem #2:
The bicyclist attempts to make a left turn and rides into the path of an oncoming motorist. The crash could occur at an intersection, a midblock driveway, or a shared-use path.

10. Bicyclist Turned or Merged Right into Path of Motorist

The bicyclist turns or merges left into the path of an overtaking motorist who is traveling straight ahead in the same direction as the bicyclist, or a bicyclist turning left strikes an oncoming motorist. This crash can also involve a bicyclist riding out from a sidewalk or path beside the road. The bicycle and the motor vehicle are initially on parallel paths.

Possible Cause/Problem #1:
The bicyclist turns or merges left from the right side of the roadway. The rider fails to see or yield to a motorist coming from behind and is hit by the overtaking motorist. The crash also could involve a bicyclist riding out from a sidewalk or path beside the road. Speed of overtaking vehicles may be a factor in this group of crashes. The motorist also may not see the bicyclist, or may not suspect that the bicyclist will turn in front in time to react.

Possible Cause/Problem #2:
The bicyclist attempts to make a left turn and rides into the path of an oncoming motorist. The crash could occur at an intersection, a midblock driveway, or a shared-use path.

11. Motorist Overtaking Bicyclist

The motorist is overtaking a bicyclist and strikes the bicyclist from behind. These crashes tend to occur because the motorist fails to detect the bicyclist, the bicyclist swerves to the left to avoid an object or surface irregularity, or the motorist misjudges the space necessary to pass the bicyclist.

Possible Cause/Problem #1:
The motorist is overtaking and fails to detect a bicyclist, striking the bicyclist from behind. These crashes often occur at night, and one or both parties may have been drinking. The bicyclist may have inadequate lights or reflectors, or may not be using lights.

Possible Cause/Problem #2:
The overtaking motorist strikes a bicyclist suddenly swerving to the left, possibly to avoid an object or surface irregularity, extended door of a parked car, or other obstacle.

12. Bicyclist Overtaking Motorist

The bicyclist is overtaking and strikes the motor vehicle from behind. These crashes tend to occur because the bicyclist tries to pass on the right or left, the bicyclist strikes a parked vehicle while passing, or the bicyclist strikes an extended door on a parked vehicle while passing.

Possible Cause/Problem #1:
The overtaking bicyclist strikes a motor vehicle while attempting to pass on either the right or the left.

13. Non-Motor Vehicle Crashes

These crashes do not involve a motor vehicle and can occur in a variety of ways, including falls from a bike, a collision between two bicycles, a collision between a bike and a pedestrian, or a bicyclist striking an object.

Possible Cause/Problem #1:
The bicyclist loses control due to a pavement surface irregularity, debris, or other hazard.

Possible Cause/Problem #2 (Other):
Either the bicyclist or the motorist was traveling in the wrong lane or direction and collided head-on with the other. The bicyclist could have been riding on the wrong side of the roadway or the motorist could have been passing another vehicle when the crash occurred.

Possible Cause/Problem #3 (Other):
Either the bicyclist or motorist made a turning error (swung too wide on a right turn or cut the corner on a left turn) and turned into the opposing lane or path of the other.

Possible Cause/Problem #4 (Other):
The bicyclist or motorist intentionally caused the crash, one or the other lost control due to impairment, mechanical problems, or other causes, or there were other unusual circumstances such as the bicyclist being struck by falling cargo. Few specific countermeasures can be identified for unusual or non-specific types of crashes other than educational and enforcement measures. To view general performance objectives and corresponding countermeasures to reduce crashes and encourage safer bicycling, go to the Performance Objectives section.